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21

To buildTo build--in reliability, electronics in reliability, electronics

manufacturers need to know as much manufacturers need to know as much

about about how things failhow things fail, as they know , as they know

how things workhow things work..

Stress Damage Model[ N = f(m,g,p,e,d) ]

Monte Carlo Simulation

Lifetime Analysis

Assessment

Reliable Component

=

CD

hTL

N

1

42

1

Yes No

Failure MechanismModel(Stress Model)

=

CN )2(2

Test Method Environmental Condition Product & Component

Material

Triangular distribution

( LD, , h )

Target

SensitivityAnalysis

DesignRevision

Test MatrixDevelopment

Failure Analysis

Accelerated Testing

Failure MechanismDetermination

[ Damage Model

]

Life Cycle Loads Structure

MaterialStress

Parameter

Variables

Reliability Assessment Process

Why failure analysis?

To identify failure modes the way the product failed

To identify failure sites where in the product failure occurred

To identify failure mechanisms the physical phenomena involved in the failure

To determine the root cause of the failure the design, defect, or loads which led to failure

To correlate failure in test to failure in the field

To aid in failure prediction and prevention

Failure Analysis Procedures

A key to understanding the results of accelerated testingA key to understanding the results of accelerated testing

Accelerated TestingAccelerated Testing

Visual InspectionVisual Inspection

Electrical TestingElectrical Testing

NonNon--Destructive EvaluationDestructive Evaluation

Destructive EvaluationDestructive Evaluation

Failure Mechanism Failure Mechanism ModelModel

Systematic Failure AnalysisSystematic Failure Analysis

Failure DistributionFailure Distribution

Reliability Growth MethodologyReliability Growth Methodology

Acceleration FactorAcceleration Factor

OBSERVED

PROBLEM

How to solve the problem?

Failure

Mechanism

Failure

Root-Cause

Failure

Mode

Failure Stresses

Load (Internal/External Stress)

Materials

(Lifetime Analysis)

(MIL-HDBK-217F )

- , ,

-

Arrhenius

Stress

, ,

(Physics-of-Failure)

Move to Science-Based Reliability

Failure Analysis ,

What is physics of failure?

, ,

: , , 100

University of Maryland, CALCE EPSC

Georgia Institute of Technology, Arizona University, NASA

Wyle Laboratory, SRI(Standford Research Institute) International

: , , 50

TRC (Toray Research Center)

Matsushita Techno Research Center

National Research Institute of Technology

University of Tokyo, Fracture Mechanics Lab.

: Fraunhofer IZM in Berlin

: ALSTOM Co. (railway test center)

Project

$4.5M

(65,000$/) 30 ~ 40 Projects

, , ( )

:

$1.4M

Electronic Products and Systems Course (1999 ISO9001 )

( )

: 12 42, 31 (2001 ) ; 73

: M. Pecht (Director, Center Chief) A. Dasgupta (Qualification and Testing)

S. Azarm (Decision Support) B. Han (Experimental Method)

R. Mroczkowski (Connectors) D. Barker (Stress Management)

Y. Joshi (Thermal Management) O. Ramahi (EMI and EMC)

D. Bigio (Polymers) E. Magrab (Manufacturing)

P. Sandborn (Cost Analysis, MEMS) P. McCluskey (Power Electronics)

CALCE EPSC (University of Maryland)

(( : : Compressor)Compressor)

:

: 10% 90% 95%

: Pd/Ps = 25/1 500hrs 2000hrs .

: ( )

:

: , Leak

: ( Stress History , )

:

?

1.

PAS(Photo Angle Sensor) IC Field

:

(1) : DPXXXXX

(2) : On Semiconductor Co., Ltd

(3) : XX PAS(Photo Angle Sensor)

(4) : open

(5) : 10EA

Photo Angle Sensor HIC

N o n - d e s t r u c t i v e A n a l y s i sN o n - d e s t r u c t i v e A n a l y s i s D e s t r u c t i v e A n a l y s i sD e s t r u c t i v e A n a l y s i s

Corrosion of Leads

Package Cracks

Shorts

Opens

ParametricShifts

ContactResistance

PackageDelamination

PackageCracking

Wire SweepBroken Wire

Wire Fatigue

Die Cracking

Corrosion

SDDV &Electromigration

Bond Crackingor Bond Lift

EOS / ESD

IntermetallicGrowth

KirkendallVoiding

Delamination& Cracking

Visual & LightMicroscopeExamination

Electrical Testing ofComponent

& Connector

X-ray Radiography

& SAM

Decapsulationthen Optical

and SEMVC & EBIC

DestructiveCross-sectionSEM & EDS

MechanicalTesting ofInternal

Components

Wire Pull

Bond Shear

Die Shear

Step 1Step 1 Step 2Step 2 Step 3Step 3 Step 4Step 4 Step 5Step 5 Step 6Step 6

2.

Electrical test (by curve tracer): Electrical open of Pin # 4 ( Reference photodiode input, 9/10 EA) Non-Destructive Inspection by Scanning Acoustic Microscope & X-Ray radiography

- SAM : Delamination on the Die paddle(top, bottom), leadframe (10/10EA)- X-ray radiography : Package crack ( 7/10 EA)

Microscopic analysis ( by SEM): Wedge bond breakage(open) of Pin # 4

[X-ray image : Package crack] [ SEM Image :Wedge bond breakage and shift of pin #4 ]

[ Electrical test : GND-Pin#4 Open ]

SPL1 SPL2 SPL3 SPL4 SPL5




SAM

IMAGE

[TOP]

SAM

IMAGE

[BOTTOM]

[ SAM IMAGE : Die paddle(top, bottom), Leadframe Delamination]

curve

open

3.

Bonding wire breakage/open due to delamination or Popcorning crack

Package delamination / Popcorning crack can (1) result in sheared or cratered ball bonds, causing electrical failures(2) lead to a long-term reliability problem, since the cracks can be a path for ionic

contamination, causing corrosion-induced failures.

Moisture IngressMoisture Absorption

During Storage

Moisture Vaporization

During Reflow Soldering

Plastic Stress Fracture/

Bonding wire open

Bonding WireOpen due to delamination

Crack

Pressure dome

Delamination/ Void

4. Failure Mechanism

When surface mount device is mounted, because the whole package is exposed to

high temperature, there are problems such as delamination of resin from frame

materials, or absorbed moisture inside package vapor blasts, resulting in

package deformation or popcorning crack.

Stress Concentration Site

Interface Delamination Site

Leadframe

Bonding WireEMC

Bonding WireBreakage/Open

Moisture Related Reliability Concerns

Bond PadCorrosion

Die MetallizationCorrosion

Cracking

Popcorning

Delamination

Tg Reduction

Field Magnetron LC Filter Feed Through

Short

Field Sample (Failure Analysis)

(Failure Mechanism)

Load-Strength Interference Model

(Accelerated Life Testing)

Review Failure HistoryReview Failure History

Failure Mechanism Failure Mechanism

Visual Inspection(Naked eye, OM)

- Mold Crack orDeformation

Non-destructive Test(X-ray)

- Epoxy Void- Crack- Terminal

- Capacitance- Dissipation Factor- Insulation Resistance- ESR

Destructive Mechanical Analysis

- Crack- Delamination

: Capacitor

Acceleration Test

Electrical Test

: Wearout : Adhesive(, Tracking)Overstress : Partial Discharge, Avalanche

Breakdown

(B10 )

: 80C ( )

Non-Destructive Test

Epoxy- (TMA)- , Tg (DSC)- (Shore-D)- Filler (TGA)- (FT-IR)

Ceramic- (TMA)- (Porosity)- (Permittivity)- Micro-Morphology- Roughness

Wearout Wearout Failure MechanismFailure Mechanism

Overstress Failure MechanismOverstress Failure Mechanism

Partial Discharge(Large Pore)

Physical Analysis

Load-Strength Interference Model( )

Determination

of Root-Cause

Adhesion depends on surface contact and surface condition

Two failure modes:

Adhesive Failure()

Cohesive Failure()

Substrate

Adhesive

BondingSurface

Substrate

Adhesive

Adhesive Failure Modes

Failure Mode

(1) : (BaTiO3, Dielectric Type : Y5U)

(2) : C , S (), T ()

(3) :

(4) : Short

(5) : 9EA

Terminal (SPCC)

GND(SPCC)

Cover (PBT)

Epoxy

Epoxy

Silicone Tube

Case(PBT)

Ceramic Capacitor

[ ] [ ]

1. Visual Inspection (Hi-scope Image)

C

[ ]

2. (X-ray Radiography)

[ ]

Capacitor

()

GND

Capacitor

Capacitor

Terminal

Terminal

Capacitor

GND

Cap. Short

Cap. Short

X-ray 2/2EA CERAMIC 7/9EA

[ : C ] [ : T]

T

Capacitance, tan & Insulation resistance

- Capacitance, tan(DF) : 10.5volts(rms), 1kHz (LCR Meter, )

- Capacitance [Spec.500pF35%.(325~675).] : (7/9EA)- tan [Spec. Max. 1%] : (7/9EA)- [Spec. Min.104M] : Short(7/9EA)

3.

(ESR : Equivalent Series Resistance) : Impedance/Gain-Phase Analyzer

T

100KHz

ESR

Capacitance

C

100KHz

ESR

Capacitance

100KHz ESR C 31, T 21. C ESR Loss T

Cross-section analysis

4.

Spark

Hi-scopeImage(C)

Cap. Epoxy

Cap. Short

Capacitor

Epoxy

Epoxy

Cap. ShortSPL2

Cap. Short

Capacitor

Epoxy

GND

Terminal

Capacitor

Hi-scopeImage(T)

- C Short , Epoxy

-T

Failure Mechanism

Tracking

, ,

Tracking

Scintillation

Spark (Arc)

Carbonization

Recrystallization(Graphitization)

Joule Heating ( +)

Capacitor Epoxy ( , Tracking )

Ceramic Epoxy Resin Ceramic-Epoxy (Ceramic : 10kV/mm, Epoxy : 16 ~ 20kV/mm)

Root-cause Analysis

RootCause

Epoxy Prepolymer Epoxide Group

Epoxy

Epoxy-Ceramic

Thermal Residual Stress

Interfacial Delamination

Ceramic : Surface Morphology,Roughness, Porosity

Epoxy : , Filler ,

Applied Electric Field

Failure

[ Pyrolysis Gas Chromatography ]

Prepolymer Bisphenol A Diglycidyl ether Monoglycidyl ether

3. TGA ( Thermogravimetry Analysis) : (thermal stability)

1) : R.T. ~800 , 20 /min scan

1. DSC (Differential Scanning Chalorimetry) : ()

1) :- 20 ~220 , 10 /min scan

2. TMA ( Thermomechanical Analysis) :

1) :- 20 ~220 , 10 /min scan, Transition

Epoxy I Epoxy II Ceramic Epoxy I Epoxy II Ceramic Epoxy I Epoxy II Ceramic53[50] 42[38] N.A. 50 45 N.A. 51 39 N.A.

Tg 41[45] 65[55] 8.6 44 43 8.8 47.8 65 8~10Tg 170[128] 158[132] 160 194 148 160

(/m)

C CapacitorS Capacitor T Capacitor

(Tg,)

Epoxy I Epoxy II Epoxy I Epoxy II Epoxy I Epoxy II 257 327 194 229 257 316

T Capacitor C CapacitorS Capacitor

()

[ ], Spec. ,N.A=not available

Micro-MorphologyMicro-Morphology

TS()

SEM image

()

SEM image

()

C S

C

C

[ : 5000 ]

[ : 5000 ]

[ : 1000 ]

[ : 2500 ]

[ : 2500 ]

[ Ceramic Dielectric : Y5U ]

DSC ( Differential scanning calorimeter ) :

- Epoxy , Enthalpy

Enthalpy

: ( 10 /min, Room Temp~ 160), 50 10 24

: 4 ( No.10)

Tg Epoxide Group

DSC : Epoxy I DSC : Epoxy II

[ (1/10EA) ] [ Tg ]

Epoxy I

Epoxy II

Tg (by DSC) Tg (by DSC)

Sample no.10

Wavenumber(cm-1)T

rans

mitt

ance

(%)

Epoxy II

Epoxy II

(by FT-IR) (by FT-IR)

Epoxy 5.80u(1740cm-1) Carbonyl

Carbonyl .

,

(1)

Conventional Approach - Mechanical Parts : Deterministic Safety Factor ( Field )- Electrical Parts : Derating ( ) Load Strength ( )

Alternative Approach- Probabilistic Model : Load Strength Load-Strength Interference Model ( )

Load Strength Random Variable

FailureMechanism

Load, Strength

ReliabilityModeling

Components

Electrical Overstress

PhV

D +=

+

=

22LS

LSR

Overstress Failure & Load-Strength Interference ModelOverstress Failure & Load-Strength Interference Model

Overstress Failure Mechanism

Limitation of Manufacturing

Large Pore Size(Agglomerate)

Partial Discharge

Gas Breakdown(Ionization)

Weak-Bond Ion

Tensile Force

Micro-Crack

Conduction Tunnel

Electrical Breakdown

Gas : ,

Sintering Temperature & Time

Paschens Law

Depolarization Field Permittivity

Dielectric Loss

Avalanche Breakdown

Electric Field(AC, dc)

Spark(V)

p*d[ Paschen ]

Vsmin

[ ]

A B C

Spark

Crack

Reliability Model

dSdLfSf

dLdSfLf

LSPLSPR

S

LS

LSL

=

=

>=>=

00

0

)(

)(

)0()(L S

L )(SfS)(LfL

Interference Area

Load & Strength(Common Units)

StrengthofpdfLoadofpdf

VariableRandomLSy ,=

dLdyLfLyf

yPR

S )()(

)0(

0 0

+=

>=

:

S

Normality Test

[ Load ][ S Strength ]

[ C Strength ]

0.843S

P Value

0.050.0780.188C

LoadStrength

[ Normality Test : Anderson-Darling ]

Load Strength

33.9 2 239(2 )

26.5 38.5(t )

71.7432.09n = 10

(C )Strength

0.018 2 0.12(2 )

5.5 5.8(t )

0.0385.66n = 10Load

1.6 2 11(2 )

18.6 21.3(t )

3.3019.93n = 10

(S )

(2) ()(S2)(X)

[ 95% Confidence Level , ] S C Partial Discharge Inception Voltage

: Sintering

+

==

22][

LS

LSSMR

9.389.38S

0.999023.12C

R(Reliability)SM(Safety Margin)

[ : kV ]

(2)

Power Law Model

Stress Power Law Model .

bfa CNS =

aS = Alternating stress

fN = Cycles to Failure

C, b = ()

b , Low Cycle Fatigue b High Cycle Fatigue b

[ b(low cycle) b(high cycle) ].

b

testa

fielda

testb

a

fieldb

a

testf

fieldf

S

S

CS

CS

N

NAF

/1

)(

)(

)(/1

)(/1

)(

)(

=

==

B

use

test

ft

fu

T

T

N

NAF

==

)(

)(aSbfCNT =

Data : Field Data(1)

=

599.1

97exp1)(

ttF

=

557.1

2028exp1)(

ttF

63.2% Characteristic Life : 97hrs

Shape Parameter () : 1.599

63.2% Characteristic Life : 2028hrs

Shape Parameter (): 1.557

HrsMTTF 871

=

+=

HrsMTTF 18221

=

+=

2187

1822===

ft

fu

N

NAF

B

u

t

TT

AF

=B

CC

=

o

o

50160

21

: -40C ~ +120C (Dwell Time 30min.)

B = 2.6 (Epoxy Ceramic )

Field Data ()

Field Mechanism(

) Mechanism

[ Field ][ Field ]

[ ] [ ] [ ]

Epoxy Ceramic Epoxy Prepolymer Epoxide Group Ceramic Epoxy ( 15)

Epoxy

Ceramic Pore Roughness Epoxy

Field Field Field

Interfacial Fracture Mechanics Approach Adhesive Failure Mechanism Time-to-failure Model , Simulation

, ,

Know-How /

, (multidisciplinary) Integration

, /

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